block: Mark bdrv_co_get_info() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_co_get_info() need to hold a reader lock for the graph.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230504115750.54437-15-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -6349,6 +6349,8 @@ int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     int ret;
     BlockDriver *drv = bs->drv;
     IO_CODE();
+    assert_bdrv_graph_readable();
+
     /* if bs->drv == NULL, bs is closed, so there's nothing to do here */
     if (!drv) {
         return -ENOMEDIUM;

block/crypto.c

@@ -736,7 +736,7 @@ fail:
     return ret;
 }
 
-static int coroutine_fn
+static int coroutine_fn GRAPH_RDLOCK
 block_crypto_co_get_info_luks(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     BlockDriverInfo subbdi;

block/io.c

@@ -727,10 +727,9 @@ BdrvTrackedRequest *coroutine_fn bdrv_co_get_self_request(BlockDriverState *bs)
 /**
  * Round a region to cluster boundaries
  */
-void coroutine_fn bdrv_round_to_clusters(BlockDriverState *bs,
+void coroutine_fn GRAPH_RDLOCK
-                            int64_t offset, int64_t bytes,
+bdrv_round_to_clusters(BlockDriverState *bs, int64_t offset, int64_t bytes,
-                            int64_t *cluster_offset,
+                       int64_t *cluster_offset, int64_t *cluster_bytes)
-                            int64_t *cluster_bytes)
 {
     BlockDriverInfo bdi;
     IO_CODE();
@@ -744,7 +743,7 @@ void coroutine_fn bdrv_round_to_clusters(BlockDriverState *bs,
     }
 }
 
-static coroutine_fn int bdrv_get_cluster_size(BlockDriverState *bs)
+static int coroutine_fn GRAPH_RDLOCK bdrv_get_cluster_size(BlockDriverState *bs)
 {
     BlockDriverInfo bdi;
     int ret;
@@ -1800,7 +1799,7 @@ fail:
     return ret;
 }
 
-static inline int coroutine_fn
+static inline int coroutine_fn GRAPH_RDLOCK
 bdrv_co_write_req_prepare(BdrvChild *child, int64_t offset, int64_t bytes,
                           BdrvTrackedRequest *req, int flags)
 {

block/mirror.c

@@ -576,8 +576,10 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
         } else if (ret >= 0 && !(ret & BDRV_BLOCK_DATA)) {
             int64_t target_offset;
             int64_t target_bytes;
+            WITH_GRAPH_RDLOCK_GUARD() {
                 bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes,
                                        &target_offset, &target_bytes);
+            }
             if (target_offset == offset &&
                 target_bytes == io_bytes) {
                 mirror_method = ret & BDRV_BLOCK_ZERO ?
@@ -966,11 +968,13 @@ static int coroutine_fn mirror_run(Job *job, Error **errp)
      */
     bdrv_get_backing_filename(target_bs, backing_filename,
                               sizeof(backing_filename));
+    bdrv_graph_co_rdlock();
     if (!bdrv_co_get_info(target_bs, &bdi) && bdi.cluster_size) {
         s->target_cluster_size = bdi.cluster_size;
     } else {
         s->target_cluster_size = BDRV_SECTOR_SIZE;
     }
+    bdrv_graph_co_rdunlock();
     if (backing_filename[0] && !bdrv_backing_chain_next(target_bs) &&
         s->granularity < s->target_cluster_size) {
         s->buf_size = MAX(s->buf_size, s->target_cluster_size);

block/raw-format.c

@@ -369,7 +369,7 @@ static BlockMeasureInfo *raw_measure(QemuOpts *opts, BlockDriverState *in_bs,
     return info;
 }
 
-static int coroutine_fn
+static int coroutine_fn GRAPH_RDLOCK
 raw_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
 {
     return bdrv_co_get_info(bs->file->bs, bdi);

include/block/block-io.h

@@ -167,8 +167,11 @@ const char *bdrv_get_node_name(const BlockDriverState *bs);
 const char *bdrv_get_device_name(const BlockDriverState *bs);
 const char *bdrv_get_device_or_node_name(const BlockDriverState *bs);
 
-int coroutine_fn bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
+int coroutine_fn GRAPH_RDLOCK
-int co_wrapper_mixed bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
+bdrv_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
+
+int co_wrapper_mixed_bdrv_rdlock
+bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi);
 
 ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
                                           Error **errp);

include/block/block_int-common.h

@@ -699,8 +699,8 @@ struct BlockDriver {
         BlockDriverState *bs, int64_t offset, int64_t bytes,
         QEMUIOVector *qiov, size_t qiov_offset);
 
-    int coroutine_fn (*bdrv_co_get_info)(BlockDriverState *bs,
+    int coroutine_fn GRAPH_RDLOCK_PTR (*bdrv_co_get_info)(
-                                         BlockDriverInfo *bdi);
+        BlockDriverState *bs, BlockDriverInfo *bdi);
 
     ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs,
                                                  Error **errp);